The invention is related to the field of wireless charger, and in particular to foreign-object detection for a resonant wireless power system.
Many electronic devices are designed to be small size, light weight and to have easy portability in order to comply with the users' requirements. Consequently, various portable electronic devices are produced by the manufacturers of the electronic devices. The common portable electronic devices include for example mobile phones, personal digital assistants (PDAs), handheld game consoles (e.g. PSP, NDSL and Gameboy series game consoles), and the like.
Due to the portability of the portable electronic device, the portable electronic device fails to be connected with the power source at any time. For providing electric power required for powering the portable electronic device, a built-in battery is usually installed in the portable electronic device. The battery is a chargeable battery. Once a power source is available, the chargeable battery of the portable electronic device may be charged by the power source as required.
For example, in a case that the residual battery capacity of the portable electronic device is insufficient, the chargeable battery of the portable electronic device may be charged by a charger. As known, conventional charger has a connecting wire. After the connecting wire is plugged in the portable electronic device and the conventional charger is connected with the power source, electric power may be transmitted from the charger to the portable electronic device through the connecting wire. However, the applications of the charger are usually restricted by the connecting wire. For example, during the process of charging the portable electronic device, the connecting wire usually becomes hindrance from operating the charger.